Vibration generating device of small wireless machine

ABSTRACT

There is provided a vibrator  10  which is integrally coupled to a rotating shaft  12  of a motor. A groove portion  13  in which the rotating shaft  12  is fitted is formed in an eccentric load portion  11,  and side walls  14  bulging from the eccentric load portion  11  and forming both side edge portions of the groove portion  13  are formed. A portion  14   c  of a tip portion end surface  14   a  of the side wall  14  except an outer peripheral portion  14   b  of the side wall  14  and at a side of the groove portion is caulked from an opening side of the groove portion to a bottom side, so that the vibrator  10  is integrally coupled to the rotating shaft.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field of the Invention

[0002] The present invention relates to a vibration generating deviceused for a call or the like of a small wireless machine, for example, aportable or mobile telephone.

[0003] 2. Prior Art

[0004] In recent years, as a kind of a small wireless machine, such as apaging system small wireless calling machine, a PHS, or a portable,mobile telephone, a machine of a type having a built-in vibrationgenerating device made by eccentrically coupling a vibrator of highspecific gravity metal to a rotating shaft of a motor becomes popular.According to the small wireless calling machine or the like having sucha built-in vibration generating device, instead of generation of aringing tone, a vibration is generated by the rotation of the vibratorso that it is possible to confirm reception without being known toanother person even in, for example, a crowd or a meeting.

[0005] Conventionally, the vibration generating device of this kind ofsmall wireless machine is constructed such that a vibrator formed into anon-cylindrical shape is integrally coupled with a rotating shaft of asmall motor connected to a signal generating circuit of the smallwireless machine. This vibrator is made of a high specific gravity metalmolded by a powder metallurgical method, a cylindrical boss portion isintegrally formed at an eccentric load portion of a substantiallyfan-shaped section, a rotating shaft is inserted into an attachment holeformed in the boss portion, and the boss portion is plastically deformedby caulking, so that the boss portion and the rotating shaft are madeclose to each other and it is integrally coupled to the rotating shaft.

[0006] According to the conventional vibration generating device likethis, since the vibrator itself is caulked and is directly coupled tothe rotating shaft, as compared with another conventional one in which avibrator is fixed to a rotating shaft through an adhesive or othercoupling parts, there is a merit that it becomes possible to reduce thenumber of parts.

[0007] However, in the above conventional vibration generating device,since the attachment hole must be formed in the inside of thecylindrical boss portion of the vibrator, there has been a problem thatwhen the vibrator is molded by pressing a powder raw material, it isdifficult to fill the powder raw material especially in a shaping dieportion of the boss portion having a thin outer periphery, and the yieldof the vibrator is lowered.

[0008] Besides, for the purpose of satisfying a demand forminiaturization in recent years, an attempt has been made to form thevibrator itself to be small. However, since the boss portion around theattachment hole becomes very thin, there has been also another problemthat when caulking is made by a large force, a crack is likely to begenerated, and on the other hand, if the caulking force is low, adesired pull-out strength can not be obtained, with the result that theadjustment of the caulking force becomes difficult.

[0009] Then, as another conventional vibration generating device, therehas been a proposal that as shown in FIG. 10 and FIG. 11, a grooveportion 4 in which a rotating shaft 3 is fitted is formed at the centerportion of an eccentric load portion 2 of a vibrator 1, side walls 5which become both side edge portions of the groove 4 are integrallyformed by bulging from the eccentric load portion 2 along the grooveportion 4. The center portions of tip portions of the side walls 5 inthe axial line direction are caulked from an opening side of the grooveportion 4 to a bottom side by a caulking punch 7 in which its tip end isshaped into an R shape (or round shape) or a rectangular parallelepipedshape, so that it is integrally coupled to the rotating shaft 3.

[0010] According to the conventional vibration generating devicedescribed above, there are merits that molding is easier than thevibrator including the boss portion in which the attachment hole isformed, so that manufacture yield can be improved, and even in the casewhere the vibrator 1 itself becomes small, as compared with the casewhere the thin portion such as the outer periphery of the boss portionis caulked, there is little fear that a crack is generated.

[0011] However, in the conventional vibration generating device shown inFIGS. 10 and 11, when the tip portion end surfaces of the side walls 5are caulked, the whole width dimensions from the sides of the groove 4to the sides of outer peripheries 6 are crushed and, therefore, a highcaulking force is required. However, since the rigidity of the portionsof the side walls 5 at the side of the groove 4 is high through therotating shaft 3, when plastic deformation is made, bulging is mainlycaused toward the sides of the outer peripheries 6 which become freeends, and as a result, there has been a problem that a high pull-outstrength can not be obtained. Besides, as a result the high caulkingforce is required, when an attempt to increase a tungsten content ismade to obtain a desired vibration even in the case where the vibrator 1is made small in diameter, it becomes brittle in material, so that therehas also been a problem that a crack is likely to be generated in thecaulked side walls 5.

SUMMARY OF THE INVENTION

[0012] The present invention has been made in view of the above, and aprincipal object of the present invention is to provide an improvementin a vibration generating device for a small wireless machine.

[0013] Another object of the present invention is to provide a vibrationgenerating device of a small wireless machine in which manufacture of avibrator is easy, the vibrator can be coupled to a rotating shaft of amotor at a high pull-out strength even by a low caulking force, and thewhole device can be further miniaturized.

[0014] According to a first aspect of the invention there is provided avibration generating device of a small wireless machine includes avibrator integrally coupled to a rotating shaft of a motor, wherein agroove portion in which the rotating shaft is fitted is formed in aneccentric load portion, side walls bulging from the eccentric loadportion and forming both side edge portions of this groove portion areformed, and a portion of a tip portion end surface of this side wallexcept an outer peripheral portion of the side wall and at a side of thegroove portion is caulked from an opening side of the groove portion toa bottom side, so that the vibrator is integrally coupled to therotating shaft.

[0015] Besides, according to a second aspect of the invention there isprovided a vibration generating device of a small wireless machine inwhich a vibrator is integrally coupled to a rotating shaft of a motor,wherein an eccentric load portion is formed into a truncated fan shapein which a center angle is less than 180° C., so that it has a flatsurface at a rotation center side, a groove portion in which therotating shaft is fitted is formed in the flat surface, side wallsforming both side edge portions of this groove portion are formed, aportion of the flat surface except an outer peripheral side portion ofthe side wall and at a side of the groove portion is caulked from anopening side of the groove portion to a bottom side, so that thevibrator is integrally coupled to the rotating shaft.

[0016] Further, according to a third aspect of the invention, which is amodification of the first aspect or second aspect of the invention,there is provided a vibration generating device of a small wirelessmachine, wherein a caulked portion formed into a concave shape in thetip portion end surface of the first aspect or the flat surface of thesecond aspect, respectively, of the invention by caulking from theopening side of the groove portion to the bottom side is formed so thata length dimension at the side of the groove in an axial line directionis longer than a length dimension at an outer peripheral side.

[0017] In the fourth aspect of the invention, in a width dimension W ofthe tip portion end surface or the flat surface as recited in any one ofthe first to third aspects, from the side of the groove to the outerperipheral side, a range of 0.25 W to 0.9 W from an edge portion at theside of the groove is caulked.

[0018] Further, in the fifth aspect of the invention, the groove portionof the vibrator as recited in any one of the first to fourth aspects isformed to have such a size as to internally contain a range exceeding acenter angle of 180° C. of the rotating shaft, and an opening width W₁of the groove portion is set so that a ratio (W₁/D) to a diameter D ofthe rotating shaft of the motor is in a range of 0.70 to 0.95.

[0019] In the vibration generating device of the small wireless machineas recited in any one of the first to fifth aspects of the invention,the rotating shaft of the motor is fitted in the groove portion, and inthe tip portion end surfaces or the flat surfaces of the side wallsforming both the side edge portions of this groove portion, the portionexcept the outer peripheral side portion and at the side of the grooveis caulked to the bottom side of the groove portion, so that as comparedwith the conventional vibration generating device shown in FIG. 10 andFIG. 11, it becomes possible to couple the vibrator to the rotatingshaft by a lower caulking force. At this time, the outer peripheralportion of the side wall which is not caulked, functions as a wallportion against the plastic deformation in the caulked portion, andconsequently, the greater part of the caulked portion is bulged to thegroove side. Then, the vibrator is firmly fixed to the rotating shaft bythree points of the bottom portion of the groove portion, and both thebulged side walls. Thus, according to the vibration generating device ofthe present invention, the manufacture of the vibration generatingdevice is easy, and further, it is possible to couple the vibrator tothe rotating shaft of the motor at a high pull-out strength even by alower caulking force.

[0020] From the above, according to the vibration generating device ofthe present invention (as recited in any one of the first to fifthaspects), since the vibrator can be firmly fixed to the rotating shaftof the motor by a lower caulking force than the prior art, it ispossible to realize the miniaturization and lightening of the vibrator,and the miniaturization and lightening of the vibration generatingdevice and the whole of the small wireless machine. Besides, as a resultthe caulking load can be made small and the generation of a crack of thevibrator can be prevented, the productivity of the vibration generatingdevice is improved, and it becomes possible to improve the vibrationefficiency by realization of the high specific gravity of the vibrator.

[0021] Here, especially in the third aspect of the invention describedabove, the length dimension of the caulked portion in the axial linedirection at the side of the groove where most portions are bulged tothe side of the rotating shaft becomes larger that at the peripheralside which functions as the wall portion when the caulked portion isplastically deformed, so that the vibrator can be coupled to therotating shaft of the motor at a high pull-out strength by a lowercaulking force. In addition, it becomes possible to use the caulkingpunch which can be easily manufactured and has a circular shape in crosssection, and the use life of the caulking punch can be greatlyelongated.

[0022] A fourth aspect of the invention is based upon any one of thefirst to third aspects of the invention described above. Namely, in thetip portion end surface or the flat surface of the side wall, when theportion except the outer peripheral side portion and at the groove sideis caulked to the bottom side of the groove portion, in the widthdimension W of the tip portion end surface or the flat surface from thegroove side to the outer peripheral side, it is preferable to caulk therange of 0.25 W to 0.9 W from the edge portion of the side of the grooveportion. At this time, in the case where the caulking width dimension issmall, it is sufficient if the caulking length dimension in the axialline direction is made large, and on the contrary, in the case where thecaulking width dimension is large, even if the caulking length dimensionin the axial line direction is small, a sufficient pull-out strength canbe obtained. The range of caulking is limited to the range of 0.25 W to0.9 W because, if the range is smaller than 0.25 W, it becomes difficultto obtain a sufficient plastic deformation amount to firmly fix thevibrator to the rotating shaft of the motor, while if the range isexceeds 0.9 W, the foregoing function as the wall portion against theplastic deformation of the caulked portion is decreased, and as aresult, the outer peripheral portion is also forcibly deformed outwardand therefore the pull-out strength is lowered.

[0023] Besides, the shapes of the side walls may be formed so that thewhole of the groove portion becomes U-shaped by erecting the sidewallsfrom both the side edges. In this case, in the state where the rotatingshaft is fitted in the groove portion, the rotating shaft is internallycontained in the groove portion within the range of a center angle of180° C. On the other hand, like the fifth aspect of the invention, whenthe groove portion of the vibrator is formed to have such a size thatthe range of the center angle of 1800 or more of the rotating shaft isinternally contained, and the opening width W₁ of the groove portion isset so that the ratio (W₁/D) to the diameter D of the rotating shaftbecomes in the range of 0.70 to 0.95, by the plastic deformation of theside wall after caulking, it is possible to fill the opening portion ofthe groove portion more effectively and to firmly fix the vibrator, sothat it is preferable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a front view showing a caulking state according to afirst embodiment of the present invention.

[0025]FIG. 2 is a longitudinal sectional view of a vibrator of FIG. 1.

[0026]FIG. 3 is a perspective view showing the first embodiment of thepresent invention.

[0027]FIG. 4 is a front view showing the shape of a vibrator accordingto a second embodiment of the present invention.

[0028]FIG. 5 is a front view showing a state where the vibrator of FIG.4 is caulked.

[0029]FIG. 6 is a front view showing the shape of a vibrator accordingto a third embodiment of the present invention.

[0030]FIG. 7 is a longitudinal sectional view of the vibrator shown inFIG. 6.

[0031]FIG. 8 is a perspective view showing a fourth embodiment of thepresent invention.

[0032]FIG. 9 is a perspective view showing a modified example of thefourth embodiment.

[0033]FIG. 10 is a front view showing a caulking state in a conventionalprior art vibration generating device.

[0034]FIG. 11 is a perspective view showing the conventional prior artvibration generating device caulked as shown in FIG. 10.

PREFERRED EMBODIMENTS OF THE INVENTION

[0035] (First Embodiment)

[0036] FIGS. 1 to 3 shows a vibrator 10 according to a first embodimentof the present invention. The vibrator 10, which is made of a highspecific gravity metal molded by a powder metallurgical technique, has asubstantially fan-shaped cross section with an axial line O as thecenter, and the whole fan-shaped portion eccentric from the axial line Obecomes or serves as an eccentric load portion 11. In the vibrator 10, agroove portion 13 in which a rotating shaft 12 of a motor is fitted andwhich has a bottom portion of a semicircle almost equal to the diameterof the rotating shaft 12 is formed at the center portion of an outerperipheral arc which depicts the fan shape of the eccentric load portion11. Further, side walls 14 which bulge from the eccentric load portion11 in parallel with each other and become opposed side edge portions ofthe groove 13 are integrally formed at both the side edge portions ofthe groove portion 13. In this kind of vibrator 10, generally, an arcradius of the eccentric load portion 11 is as very small as several mm,and consequently, it is difficult to distinguish between vibrators ofdifferent sizes, so that concave identification marks 16 of variousshapes (circle in the drawing) indicating the size of the vibrationgenerating device 10 are formed at both end surfaces of the eccentricload portion 11.

[0037] Then, in a tip portion end surface 14 a of the side wall 14, andat the center portion except both end portions in the direction of theaxial line O, a portion 14 c except an outer peripheral side portion 14b of the side wall 14 and at the side of the groove 13 is caulked by arectangular parallelepiped caulking punch 15 from an opening side of thegroove 13 to a bottom side, so that the above vibrator 10 is integrallycoupled to the rotating shaft 12. Here, in a width dimension W of thetip portion end surface 14 a from the side of the groove portion 13 tothe outer peripheral side, the portion 14 c to be caulked at the side ofthe groove portion 13 is set in the range of 0.25 W to 0.9 W from theedge portion at the side of the groove 13.

[0038] Incidentally, the rotating shaft 12 can be made of stainless, forexample, SUS 420 or the like. Besides, the vibrator 10 is preferablymolded by using an ultra heavy alloy material of a specific gravity ofabout 17 to 19 g/cm 3, for example, W-Ni system, W-Ni-Fe system, W-Ni-Cusystem, W-Mo-Ni-Fe system, or the like and by a powder metallurgicaltechnique. Specifically, a mixture powder of a composition made of: Wpowder of 89 to 98 weight %, and Ni powder of 1.0 to 11 weight %, or amixture powder of a composition containing the W powder and Ni powder inthe above range of weight %, and one or more kinds of Cu of 0.1 to 6weight %, Fe powder of 0.1 to 6 weight %, Mo powder of 0.1 to 6 weight%, and co powder of 0.1 to 5 weight % is or are compacted into a fanplate shape by a pressure of 1 ton/cm2 to 4 ton/cm2, and this compact isliquid phase sintered in a hydrogen gas stream of a dew point of 0° C.to −6° C. or an ammonia decomposition gas, and thereafter, it is furtherheated in the temperature range of 700° C. to 1430° C. ± 30° C. in avacuum, neutral or reducing atmosphere, and then, a heat treatment ofrapidly cooling it to at least 300° C. at a cooling rate of 40° C./minor more is performed.

[0039] In the composition of the vibrator 10 like this, when the W(tungsten) content exceeds 98 weight %, the specific gravity becomeshigh although the malleability (or ductility) is lowered, and in thecase where it is less than 89 weight %, a predetermined specific gravitycan not be obtained, and it becomes disadvantageous as this kind ofvibrator. Besides, also in the case where the N (nickel) content exceeds11 weight %, a predetermined specific gravity can not be obtained, andin the case where it is less than 1.0 weight %, sintering does notproceed. Further, although Co (cobalt) has the same effect as Ni, whenit is less than 0.1 weight %, a sufficient effect of the addition cannot be obtained, and on the other hand, even if it exceeds 5 weight %,an adequate effect can not be obtained and the manufacture becomesuneconomical. When the Cu powder and Fe powder are contained, although asintering temperature can be lowered, a predetermined specific gravitycan not be obtained in a range over the above upper limit value.

[0040] According to the vibration generating device of the smallwireless machine having the above structure of composition, the rotatingshaft 12 of the motor is fitted in the groove 13, and in the tip portionend surfaces 14 a of the side walls 14 forming both the side edgeportions of the groove portion 13, except the outer peripheral sideportion 14 b, in the width dimension W from the side of the groove 13 tothe outer peripheral side, the portion 14 c in the range of 0.25 W to0.9 W from the edge portion at the side of the groove 13 is caulked bythe caulking punch 15 toward the bottom side of the groove 13, so thatas compared with the conventional vibration generating device as shownin FIGS. 10 and 11, it is possible to couple the vibrator to therotating shaft by a lower caulking force.

[0041] At this time, since the outer peripheral portion 14 b of the sidewall, which is not caulked, functions as a wall portion against theplastic deformation in the caulked portion 14 c, the greater part of thecaulked portion 14 c is bulged to the side of the groove 13, andconsequently, the vibrator 10 can be firmly fixed to the rotating shaft12 by three points of the bottom portion of the groove 13, and both thebulged side walls. Thus, manufacture of the vibrator 10 is easy, and thevibrator can be coupled to the rotating shaft of the motor at a highpull-out strength even by a low caulking force.

[0042] According to the vibration generating device described above,since the vibrator 10 can be firmly fixed to the rotating shaft 12 by alower caulking force than the prior art, miniaturization and lighteningof the vibrator 10 itself, and further, miniaturization and lighteningof the vibration generating device and the whole of the small wirelessmachine can be realized. Besides, since the caulking load is made smalland the generation of a crack in the vibrator 10, especially at the sidewall 14 can be prevented, it becomes possible to increase theproductivity of the vibration generating device and to improve thevibration efficiency through realization of the high specific gravity ofthe vibrator 10.

[0043] Experiment

[0044] An experiment was made in which the pull-out strength of thevibrator 10 fixed to the rotating shaft 12 by the caulking according tothe present invention was compared with the pull-out strength of theconventional vibrator 1 fixed to the rotating shaft 3 by theconventional caulking shown in FIGS. 10 and 11. In the comparisonexperiment, by using the vibrators 1 and 10 and the rotating shafts 3and 12 respectively having the same shape, five vibration generatingdevices were produced in each group.

[0045] In the above vibrators 1 and 10 used for the experiment, theouter diameter of each of the eccentric load portions 2 and 11 was 3 mm,the length in the direction of the axial line O was 5 mm, the innerdiameter of each of the grooves 4 and 13 was 0.4 mm, the heightdimension of each of the side walls 5 and 14 from the bottoms of thegrooves 4 and 13 was 1.1 mm, the width dimension W of each of the sidewalls 5 and 14 was 0.7 mm, and the outer diameter dimension of each ofthe rotating shafts 3 and 12 was 0.8 mm.

[0046] Besides, in the conventional vibration generating device, theside wall 5 extending over the whole width dimension was crushed in alength of 2.6 mm in the axial line direction by the caulking punch 7. Onthe other hand, in the vibration generating device of the presentinvention, by using the caulking punch 15 with a width size of 1.4 mm,the range (0.43 W) of 0.3 mm of the respective side walls 14 from theside of the groove portion 13 was crushed in a length of 2.0 mm in theaxial line direction.

[0047] With respect to the five vibration generating devices in eachgroup obtained in this way, a pull-out test of the conventionalvibrators 1 and the inventive vibrators 10 was carried out, and it wasfound that while the extracting force (kgf) was 5.3, 4.9, 5.5, 5.5, 5.4(average 5.3) in the conventional vibration generating device, theextracting force (kgf) was 10.3, 11.0, 10.5, 10.3, 10.2 (average 10.5)in the vibration generating device of the present invention, that is, inspite of the fact that the caulking length in the axial line directionwas shorter by 0.6 mm, the pull-out strength almost twice theconventional pull-out strength was obtained.

[0048] Second Embodiment

[0049]FIGS. 4 and 5 show a second embodiment of the present invention,and in this vibration generating device, a groove portion 22 having abottom portion 22 a of a substantially semicircular shape is formed inan eccentric load portion 21 of a vibrator 20, and side walls 23 formingboth side walls of this groove portion 22 are integrally formed so as tocover an exposed portion of a rotating shaft 24 of a motor fitted in thegroove 22 with an interval from both sides in the direction of an axialline O. As a result, the groove portion 22 of the vibrator 20 is formedto have such a size as to internally contain the range of a center angle180° C. or more of the rotating shaft 24. An opening width W₁ of thegroove portion 22 between the opposite side walls 23 is set so that aratio (W₁/D) to a diameter D of the rotating shaft 24 is in the range of0.70 to 0.95.

[0050] As a specific example in which such a range is obtained, in thecase where the diameter D (mm) of the rotating shaft 24 is 0.4, 0.5,0.6, 0.7, 0.8, 0.9 or 1.0, it is sufficient if the opening width W₁ (mm)of the groove portion 22 between the side walls 23 is set to 0.3, 0.4,0.5, 0.6, 0.7, 0.8, or 0.9.

[0051] As shown in FIG. 5, in a tip portion end surface 23 a of the sidewall 23, and at the center portion except both ends in the direction ofthe axial line O, a portion 23c except an outer peripheral side portion23 b of the side wall 23 and at the side of the groove 22 is caulked bya rectangular parallelepiped caulking punch 25 from an opening side ofthe groove 22 to a bottom side, so that the above vibrator 20 isintegrally coupled to the rotating shaft 24. At this time, similarly tothe first embodiment, in a width dimension W of the tip portion endsurface 23 a from the side of the groove portion 22 to the outerperipheral side, the caulked portion 23 c at the side of the groove 22is set so that it is in the range of 0.25 W to 0.9 W from an edgeportion at the side of the groove 22.

[0052] Also in the vibration generating device having the abovestructure shown in FIGS. 4 and 5, the same function and effect as thoseof the first embodiment can be obtained, and especially in the vibrator20 of the second embodiment, the groove portion 22 of the vibrator 20 isformed to have such a size as to internally contain the range of acenter angle of 180° C. or more of the rotating shaft 24, and theopening width W₁ of the groove portion 22 is set so that the ratio(W₁/D) to the diameter D of the rotating shaft 24 is in the range of0.70 to 0.95, so that the vibrator 20 is firmly fixed to the rotatingshaft 24 by three points of the bottom portion 22 a of the grooveportion 22, and bottom portions 23 d of the side walls 23. As a result,it is possible to fix the vibrator 20 to the rotating shaft 24 by alower caulking force.

[0053] Third Embodiment

[0054]FIGS. 6 and 7 show a vibrator 30 of a third embodiment, and inthis vibrator 30, the whole of an eccentric load portion 31 is formedinto a shape of a truncated fan-shaped cross section in which a centerportion, indicated by a dotted line in the drawing, of a fan shape witha center angle of less than 180° C. is removed. By this, flat surfaces32 are formed at the rotation center side of the vibrator 30, and aU-shaped groove portion 33 in which the rotating shaft is fitted isformed at the center of this flat portions 32. As a result, side walls34 forming both side edge portions of the groove portion 33 are formedat both sides of this groove portion 33, and an outer peripheral surface34 a of the side wall 34 is formed into a slant flat surface shape whichis continuous with an outside surface 31 a of this eccentric loadportion 31 and leads to an arc-shaped outer peripheral surface 31 b.

[0055] Similarly to the first embodiment, in the flat surface 32 whichbecomes a tip portion end surface of the side wall 34, and at the centerportion except both end portions in the axial line direction, a portionof the side wall 34, except a portion at the side of the outerperipheral surface 34 a, at the side of the groove portion 33 is caulkedby a rectangular parallelepiped caulking punch from the opening side ofthe groove portion 33 to the bottom side, so that the above vibrator 30is integrally coupled to the rotating shaft. Also in this vibrator 30,in the width dimension W of the flat surface 32 from the side of thegroove portion 33 to the outer peripheral side, the caulked portion atthe side of the groove 33 is set so that it is in the range of 0.25 W to0.9 W from the edge portion at the side of the groove 33.

[0056] Also in the vibration generating device made of the abovestructure of the third embodiment of the invention, the same functionand effect as those shown in the first embodiment can be obtained, andfurther, the whole of the vibrator 30 is formed into the shape havingthe center angle of less than 180° C. and having the truncatedfun-shaped cross section in which the flat portion 32 is formed at thecenter portion. Therefore, there are such advantages that a metal moldshape for forming the vibrator 30 by powder molding is simplified, andmanufacture becomes easy. Further, since the center of gravity can beset at a position decentered (or eccentric) from the rotating shaft tothe outside, a desired vibration can also be obtained.

[0057] Fourth Embodiment

[0058]FIGS. 8 and 9 show a vibrator 40 according to a fourth embodimentof the invention and its modified example, respectively. The vibrator 40has substantially the same shape as that shown in the first embodiment,and the entire of a fan-shaped portion eccentric from its axial line isan eccentric load portion 41. In the vibrator 40, a semicircular grooveportion 43 in which a rotating shaft 42 of a motor is fitted and whichhas a bottom portion with a size substantially equal to a diameter ofthe rotating shaft 42 is formed at the center portion of an outerperipheral arc which depicts the fan shape of the eccentric load portion41. Side walls 44 bulging from the eccentric load portion 41 in parallelwith each other and becoming both side edge portions of the groove 43are integrally formed at both side edge portions of the groove portion43.

[0059] Then, in a tip portion end surface 44 a of the side wall 44, andat the center portion except both end portions in an axial linedirection, a portion 44c of the side wall 44 except an outer peripheralside portion 44b and at the side of the groove 43 is caulked by acylindrical caulking punch 45 from an opening side of the groove 43 to abottom side, so that the above vibrator 40 is coupled to the rotatingshaft 42. Here, as a result of caulking by the cylindrical caulkingpunch 45, the concave caulked portions 44 c formed at the tip portionend surfaces 44 a respectively become substantially semi-circular, andare formed so that a length dimension L in the axial line direction atthe side of the groove portion 43 becomes larger than a length dimensionat the outer peripheral side.

[0060] Besides, in a vibrator 40 shown in FIG. 9, at the center portionof a tip portion end surface 44 a, a portion 44 c′ of a side wall 44except an outer peripheral side portion 44 b and at the side of a groove43 is caulked by a caulking punch 46 in a state where a corner portionof the caulking punch 46 having a square section is positioned at theouter peripheral side, so that it is integrally coupled to a rotatingshaft 42. By this, the concave caulked portion 44 c′ formed by caulkingwith the caulking punch 46 is formed into a triangular shape having abottom side at the side of the groove 43.

[0061] As a result, according to the above vibration generating devicesshown in FIG. 8 and FIG. 9, the same function and effect as those shownin the first and second embodiments are obtained, and further, thelength dimensions of the caulked portions 44 c and 44 c′ are formed sothat the dimension at the side of the groove 43 where most parts arebulged to the side of the rotating shaft 42 becomes larger than that atthe outer peripheral side functioning as a wall portion when the caulkedportions 44 c and 44 c′ are plastically deformed, so that the totalvolume to be plastically deformed becomes small, and a high pull-outstrength can be obtained by a further low caulking force. In addition,it is possible to use the caulking punch 45 which is easily manufacturedand has the circular section, and it is also possible to greatly enlargethe use life of the caulking punches 45 and 46.

[0062] With respect to the vibrators 10, 20, 30 and 40 in the first tofourth embodiments of the invention, although the description has beenmade only on the case where the eccentric load portions 11, 21, 31, and41 having the substantially fan-shaped section or truncated fan-shapesection are formed, the invention is not limited to this, but it ispossible to use some other modified structures including eccentric loadportions of various shapes, for example, a substantially semi-circularsection or the like.

[0063] Besides, also with respect to the groove portions 13, 22, 33, and43, the bottom portions are not limited to the semi-circular shape, butthey can be formed into various sectional shapes, such as asubstantially square section or a substantially trapezoid section.

[0064] Effect of the Invention

[0065] As described above, according to the vibration generating deviceof the small wireless machine as recited in any one of first to fifthaspects of the invention, since the vibrator can be firmly fixed to therotating shaft of the motor by a lower caulking force than the priorart, miniaturization and lightening of the vibrator, and miniaturizationand lightening of the vibration generating device and the entire of thesmall wireless machine can be realized, and a caulking load can be madesmall and the generation of a crack of the vibrator can be prevented,and consequently, the productivity of the vibration generating devicecan be improved, and it becomes possible to improve the vibrationefficiency by realization of the high specific gravity of the vibrator.

[0066] Here, especially according to the invention as recited in thethird aspect of the invention, the vibrator with a high pull-outstrength can be coupled to the rotating shaft of the motor by a furtherlow caulking force, and further, it becomes possible to use the caulkingpunch which is easily manufactured and has the circular section, and theuse life of the caulking punch can be greatly elongated.

[0067] Besides, according to the invention as recited in the fifthaspect of the invention, the groove portion of the vibrator is formed tohave such a size as to internally contain the range of the center angleof 180° C. or more of the rotating shaft, and the opening width W₁, ofthe above groove portion is set so that the ratio (W₁/D) to the diameterD of the rotating shaft is in the range of 0.70 to 0.95, so that it ispossible to obtain an effect that after caulking, the opening portion ofthe groove portion is further effectively filled by the plasticdeformation of the side wall and the vibrator can be firmly fixed.

What is claimed is:
 1. A vibration generating device of a small wirelessmachine with a vibrator integrally coupled to a rotating shaft of amotor, comprising: an eccentric load portion, a groove portion, forsecuring therein the rotating shaft, in the eccentric load portion, sidewalls bulging from the eccentric load portion and forming both side edgeportions of the groove portion, wherein a portion of a tip portion endsurface of the side wall except an outer peripheral portion of the sidewall and at a side of the groove portion is caulked from an opening sideof the groove portion to a bottom side, so that the vibrator isintegrally coupled to the rotating shaft.
 2. A vibration generatingdevice of a small wireless machine with a vibrator integrally coupled toa rotating shaft of a motor, comprising: an eccentric load portionhaving a truncated fan shape in which a center angle is less than 180°C., so that it has a flat surface at a rotation center side, a grooveportion, for receiving therein the rotating shaft, on the flat surface,side walls forming both side edge portions of the groove portion,wherein a portion of the flat surface except an outer peripheral sideportion of the side wall and at a side of the groove portion is caulkedfrom an opening side of the groove portion to a bottom side, so that thevibrator is integrally coupled to the rotating shaft.
 3. A vibrationgenerating device of the small wireless machine according to claim 1 or2, wherein a caulked portion is formed into a concave shape in the tipportion end surface or the flat surface by caulking from the openingside of the groove portion to the bottom side so that a length dimensionat the side of the groove in an axial line direction becomes longer thana length dimension at the outer peripheral side.
 4. A vibrationgenerating device of the small wireless machine according to claim 1 or2, wherein in a width dimension W of the tip portion end surface or theflat surface from the side of the groove to the outer peripheral side, arange of 0.25 W to 0.9 W from an edge portion at the side of the grooveis caulked.
 5. A vibration generating device of the small wirelessmachine according to claim 1 or 2, wherein the groove portion of thevibrator is formed to have such a size as to internally contain a rangeexceeding a center angle of 180° C. of the rotating shaft, and anopening width W₁ of the groove portion is set so that a ratio (W₁/D) toa diameter D of the rotating shaft of the motor is in a range of 0.70 to0.95.